For several years now the U.S. Navy has been planning to replace older attack and cruise-missile submarines with an improved version of the cutting-edge Virginia-class undersea boat. And in late October, Adm. David Johnson, the sailing branch’s top sub-builder, finally unveiled the new vessel’s possible configurations during a conference in Virginia.

Options for the so-called “Block V” Virginias range from a nearly 480-foot-long behemoth to a simpler model that’s just 450 feet from bow to stern. But all five proposed designs are longer than today’s standard Virginias, which measure just 380 feet. And for a good reason. The Block Vs—the Navy wants to build 10 of them between 2019 and 2023—are expected to include a structural plug, known as a “payload module,” inserted in the middle of the standard nuclear-powered Virginia design. The module is meant to accommodate four vertical tubes that open to the water and can be accessed from inside the ship.

These payload tubes could carry sea-launched robots, divers or—most significantly—seven Tomahawk cruise missiles apiece. Combined with the six-round tubes already installed in the bow of a standard Virginia, a fully missile-loaded module would boost a sub’s Tomahawk count to an impressive 40 missiles. Each maneuverable, GPS-guided Tomahawk can fly a thousand miles at low level and hit a target with pinpoint accuracy. The Navy wants the missile-heavy Block V subs to replace the current fleet of four dedicated cruise-missile submarines.

Very interesting. It'll be interesting to see which choice is selected. I can't imagine more than a handful would be built and that the obvious choice would be the one that causes the least disruption to the baseline design since that will be the cheapest.